| Safe Haskell | Safe-Inferred |
|---|---|
| Language | Haskell2010 |
Data.Universe.Helpers
- universeDef :: (Bounded a, Enum a) => [a]
- interleave :: [[a]] -> [a]
- diagonal :: [[a]] -> [a]
- diagonals :: [[a]] -> [[a]]
- (+++) :: [a] -> [a] -> [a]
- (+*+) :: [a] -> [b] -> [(a, b)]
- choices :: [[a]] -> [[a]]
- unfairCartesianProduct :: [a] -> [b] -> [(a, b)]
- unfairChoices :: [[a]] -> [[a]]
Documentation
This module is for functions that are useful for writing instances, but not necessarily for using them (and hence are not exported by the main module to avoid cluttering up the namespace).
universeDef :: (Bounded a, Enum a) => [a] Source
For many types, the universe should be [minBound .. maxBound];
universeDef makes it easy to make such types an instance of Universe via
the snippet
instance Universe Foo where universe = universeDef
interleave :: [[a]] -> [a] Source
Fair n-way interleaving: given a finite number of (possibly infinite)
lists, produce a single list such that whenever v has finite index in one
of the input lists, v also has finite index in the output list. No list's
elements occur more frequently (on average) than another's.
diagonal :: [[a]] -> [a] Source
Unfair n-way interleaving: given a possibly infinite number of (possibly
infinite) lists, produce a single list such that whenever v has finite
index in an input list at finite index, v also has finite index in the
output list. Elements from lists at lower index occur more frequently, but
not exponentially so.
diagonals :: [[a]] -> [[a]] Source
Like diagonal, but expose a tiny bit more (non-semantic) information:
if you lay out the input list in two dimensions, each list in the result
will be one of the diagonals of the input. In particular, each element of
the output will be a list whose elements are each from a distinct input
list.
(+*+) :: [a] -> [b] -> [(a, b)] Source
Slightly unfair 2-way Cartesian product: given two (possibly infinite)
lists, produce a single list such that whenever v and w have finite
indices in the input lists, (v,w) has finite index in the output list.
Lower indices occur as the fst part of the tuple more frequently, but not
exponentially so.
choices :: [[a]] -> [[a]] Source
Slightly unfair n-way Cartesian product: given a finite number of
(possibly infinite) lists, produce a single list such that whenever vi has
finite index in list i for each i, [v1, ..., vn] has finite index in the
output list.
unfairCartesianProduct :: [a] -> [b] -> [(a, b)] Source
Very unfair 2-way Cartesian product: same guarantee as the slightly unfair
one, except that lower indices may occur as the fst part of the tuple
exponentially more frequently. This mainly exists as a specification to test
against.
unfairChoices :: [[a]] -> [[a]] Source
Very unfair n-way Cartesian product: same guarantee as the slightly unfair one, but not as good in the same sense that the very unfair 2-way product is worse than the slightly unfair 2-way product. Mainly for testing purposes.